How about an article about time-length of Outland instance runs. I'm a casual player. Married to a tolerant non-gamer, two kids. I probably play 2-3 times a week for 1.5 hours at a stretch. My Shaman is 62, but I've only completed one instance (ZF). I've also mostly completed SFK and ST.While we are in the middle of a heated debate on difficulty of 5-man groups, we tend to forget some basic truths. The most basic truth about instances is that playing in a group is more difficult than playing solo. Which for many of us is actually the attraction of it. A solo combat, only you against a single mob, is easy to the point of being boring. You know your spells and abilities, there usually aren't all that many of them, and most of the time you have a generous amount of time to hit the next button. One time this week I started a combat with my warrior against an even level demon, and after the first few exchanges of blows, my connection broke down. Had to reboot the computer and log back in, only to find that the warrior had won the combat in my absence, just by auto-attack. (Don't try that with a mage).
I had read that Blizzard intended that BC 5-mans would be much shorter. And someone in the Shaman forums said the same thing. That a good group can clear a non-heroic in 45-60 minutes. Is this your experience? I've tried Ramparts on two separate occasions, but both groups fell apart. (The latter was this weekend... my Elemental Shaman (MH) and the Dual-Wielding Warrior (tank) knew what we were doing but were improperly spec'ed, exactly like your recent post).
Anyway, if you have any thoughts on time-to-complete of BC 5-mans, I'd love to read them.
Group combat is a lot more difficult. Basically it is all about aggro management, forcing the mobs to keep hitting the tank with the high damage absorption capacity, and not the squishy mages and healers. That means that people have to time their spells better, for example not use their largest damage abilities right at the start before the tank has aggro. There is a lot more coordination required, giving you less time to decide on the right action and less room for error. You can't simply have 5 people doing the same as they would do in a solo combat.
Fighting in an instance with a group being more difficult and there being a higher chance to wipe has a big impact on how long it takes to complete a dungeon. I simply don't feel comfortable saying "you can do Hellfire Ramparts in 60 minutes". I know *I* can do Hellfire Ramparts in 60 minutes, in a guild group, especially if I'm going with my warrior and am able to set the pace. (When I'm playing my priest I have a lot less influence on the pace, as I shouldn't pull.) But if you go with a pickup group, Hellfire Ramparts can easily take 2 hours instead of 1.
Group coordination being so essential, and difficult, going somewhere with guild mates, people you already played with, is making things a lot easier. Coordination is something that needs a bit of practice. In the ideal case you get a pickup group where all the players are playing reasonably well, somebody is taking the lead, and after a few combats the coordination works well enough. More commonly coordination takes a couple of wipes, learning from mistakes, because everyone in the group isn't the most experienced group player, and nobody is really leading, or some people don't follow the leader's instructions. Every wipe costs some time.
And then, you already mentioned it, is the possibility of pickup groups falling apart. You wipe a few times, and somebody gets fed up and leaves. Or somebody has something real life coming up, like a kid having forgotten all about dinner time and his parents forcing him to quit playing. When somebody leaves at the very least you'll need some time to replace him, and if you can't find a replacement fast, other people are likely to leave and the whole group falls apart. So the time to complete that dungeon goes up to forever.
While I can't tell you exactly how long you'll need for the Burning Crusade instances, I can tell you that they are significantly shorter than the old world dungeons. 5-man instances in Burning Crusade all have between 2 and 4 bosses, with most having 3 of them. That makes them about half the size of Zul'Farrak, and needing only half the time. Which is a nice improvement from Blizzard, as it gives people with shorter playing sessions a better shot at being able to finish a dungeon.